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सी.आई.एस.सी.ई.आयसीएसई ICSE Class 7

How Do You Say that the Process of Digestion is a Chemical Change ? - Chemistry

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प्रश्न

How do you say that the process of digestion is a chemical change ?

टीपा लिहा

उत्तर

During digestion new substances are formed which cannot be converted back to the same food which we have eaten. Besides energy is also released. These factors prove that digestion is a chemical change.

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पाठ 2: Physical and Chemical Changes - Additional questions 8

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सेलिना Concise Chemistry [English] Class 7 ICSE
पाठ 2 Physical and Chemical Changes
Additional questions 8 | Q 5

संबंधित प्रश्‍न

Give two reasons to justify water at room temperature is a liquid.


What do you mean by the change of state? Write the flow chart showing the complete cycle of change of state.


What do you observe when :

water is boiled


Dissolving salt in water is a reversible change.


Does the substance absorb or liberate any heat energy during the change of phase?


Convert the temperature of 573 K to the Celsius scale.


Which contains more heat, 1 kg of water at 100° C or 1 kg of steam at 100° C ? Give reason for your answer.


Define the following term Boiling.


What are the two ways in which the physical states of matter can be changed ?


Which of the following process/processes release heat ?

  1. condensation
  2. vaporisation
  3. freezing
  4. melting

The boiling point of ethane is – 88°C. This temperature will be equivalent to :


When heat is constantly supplied by a gas burner with small flame to melt ice, then the temperature of ice during melting :


When water is heated to a temperature x, it gets converted into steam at temperature x by a process called R. And when steam at temperature x is cooled, it gets reconverted into water at the same temperature x by a process called S.

  1. How much is the value of x in Kelvin ?
  2. What is the process R called ?
  3. What is the name of the energy absorbed during the process R ?
  4. What is process S known as ?
  5. What is the name of energy released during the process S known as ?\\

Write whether the following statement is true or false:

A gas has no free surface.


Fill in the blank with the correct word Given below.

Intermingling of molecules is called ____


State the property of the following substance.

Lead chloride reacts with barium sulphate to give a white precipitate of lead sulphate.


In the paragraph below, write ‘solid’, ‘liquid’ or ‘gas’ in each of the brackets depending on the substance referred to just before.

On a bright sunny day, Riya and Gargi are playing with a ball ( ) in the park. Gargi feels thirsty. So, Riya brings tender coconut water ( ) for her. At the same time, a strong breeze ( ) starts blowing and it also begins to rain ( ). They run back into the house ( ), change their clothes ( ), and then their mother gives them a cup ( ) of hot milk ( ) to drink.


Why does this happen?

What you see in the picture.


State whether the following statement is true or false. If false write the correct statement.

During a chemical change the composition of the original substance is not altered and the change is irreversible.


With reference to the liquid state of matter – answer the following

On heating, the liquid, do the particles gain or lose energy.


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